Implantable medical lead having reduced dimension tubing transition

ABSTRACT

Lead body designs for forming a fluid tight seal between a multilumen tube and other portions of a lead body are provided. One lead body design has a multilumen tube having a first portion defining a first number of lumens and a second reduced dimension portion defining a second number of lumens, the second number of lumens being smaller than the first number of lumens. The reduced dimension portion is attached to a distal tip portion of the lead body, forming a fluid tight passageway through the multilumen tube to the distal tip portion. Also provided are methods for forming such multilumen tubes and incorporating such multilumen tubes into a lead body.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Provisional Application No.61/089,330, filed Aug. 15, 2008, which is herein incorporated byreference in its entirety.

BACKGROUND

Medical leads typically have an elongate lead body that is used todeliver a therapy (e.g., one or more electrical pulses) to a location ofinterest within a patient. Many leads have one or more electrodes (e.g.,ring electrodes or coil electrodes) disposed along the lead body. Somesuch leads also have a fixation member (e.g., an active fixation member)at the distal end of the lead body for fixing the lead body at a desiredlocation within a patient's body. There is a need in the art foralternative designs and methods of construction for leads.

SUMMARY

In one embodiment of the invention, a medical lead comprises amultilumen tube having a distal end and a proximal end and a wall. Thewall defines at least three lumens along a first longitudinal portion ofthe tube and less than three lumens along a second longitudinal portionof the tube. A first, continuous lumen extends through both the firstand second portions and the wall is substantially continuous throughboth the first and second longitudinal portions. A proximal connector isdisposed at the proximal end of the medical lead and the proximalconnector is adapted to connect the lead to an implantable medicaldevice. A fixation member is disposed on a distal end of the lead bodyand the fixation member has a fixation helix that is adapted to fix thelead at a site within a patient. A conductor member is disposed in thecontinuous lumen and electrically couples the proximal connector to thefixation member. The medical lead also has a distal tip portion, and thefixation member at least partially disposed within the distal tipportion. The second portion of the multilumen tube is connected with thedistal tip portion, providing a fluid-tight passageway extending throughthe first and second portions of the multilumen tube and into the distaltip portion.

In another embodiment of the present invention, a medical lead comprisesa multilumen tube defining a first number of lumens along a firstlongitudinal portion of the tube and a second number of lumens along asecond longitudinal portion of the tube. The first number of lumens islarger than the second number of lumens. A continuous lumen extendsthrough both the first and second portions and the wall is substantiallycontinuous through both the first and second longitudinal portions. Afixation member is disposed on a distal end of the lead body, and thefixation member has a fixation helix that is adapted to fix the lead ata site within a patient. The medical lead also has a distal tip portion,and the fixation member at least partially disposed within the distaltip portion. A fluid tight seal is formed between the second portion ofthe multilumen tube and the distal tip portion, providing a fluid-tightpassageway through the first and second portions of the multilumen tube,into the distal tip portion and to the fixation member.

In yet another embodiment of the present invention, a method ofmanufacturing a medical lead comprises providing a multilumen tubehaving a distal end and a proximal end and a first longitudinal axis,the tube defining a lumen that defines a second longitudinal axis thatis non-coaxial with the first longitudinal axis. The method furthercomprises removing a first portion of a cross-section of the tube alonga desired portion of the length of the tube while maintaining the lumen.The multilumen tube is rotated about the second longitudinal axis and asecond portion of a cross-section of the tube is removed along thedesired portion of the length of the tube. The multilumen tube isincorporating the tube into a lead.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a medical lead according to embodiments of thepresent invention;

FIG. 2 is a longitudinal cross-sectional view of a distal portion of amedical lead according to embodiments of the present invention;

FIG. 3 is a cross-sectional view of a portion of the distal portion ofFIG. 2 according to some embodiments of the present invention;

FIGS. 4A-4C are cross-sectional views of a portion of the distal portionof FIG. 2 according to various embodiments of the present invention;

FIG. 5 is a longitudinal cross-sectional view of a proximal portion of alead according to some embodiments of the present invention;

FIG. 6 is a longitudinal cross-sectional view of a portion of anelectrode according to some embodiments of the present invention;

FIGS. 7A and 7B are cross-sectional views of a portion of the electrodeof FIG. 6 according to some embodiments of the present invention; and

FIG. 8 is a perspective view of a fixture according to some embodimentsof the present invention.

While the invention is amenable to various modifications and alternativeforms, specific embodiments have been shown by way of example in thedrawings and are described in detail below. The intention, however, isnot to limit the invention to the particular embodiments described. Onthe contrary, the invention is intended to cover all modifications,equivalents, and alternatives failing within the scope of the inventionas defined by the appended claims.

DETAILED DESCRIPTION

FIG. 1 shows a medical lead 1 according to embodiments of the presentinvention. The medical lead 1 has a lead body 3 with a distal portion 5and a proximal portion 7. A fixation helix 9 is disposed on the leadbody distal portion 5. The fixation helix 9 is configured to anchor thelead body 3 at a desired location within a patient, as further discussedbelow.

In addition, the lead 1 has a proximal connector 11 disposed on the leadbody proximal portion 7. The proximal connector 11 is configured tocouple to a cardiac rhythm management device (not shown). The proximalconnector 11 has a connector body 13 and a terminal pin 14 extendingproximally from the connector body 13. In some embodiments, and as shownin FIGS. 1 and 5, the connector body 13 has a larger outer dimensionthan the terminal pin 14.

As shown in FIG. 1, the terminal pin 14 includes a single electricalcontact 15. In other embodiments, the terminal pin 14 has more than one,or two or more, electrical contacts formed thereon. Further, as shown inFIG. 1, the proximal connector body 13 has two ring contacts 16 disposedthereon. In other embodiments, the proximal connector body 13 has asingle, one or more, two or more, or three or more electrical contacts16 disposed thereon.

Further, the lead 1 has one or more electrodes disposed thereon, forexample two electrodes 17, 19 as shown in FIG. 1. In other embodiments,the lead 1 has more than two, three or more, or four or more electrodes,or any other suitable number of electrodes. In some exemplaryembodiments, one or more of the electrodes 17, 19 are shock coils thatare disposed along the lead body 3. In other exemplary embodiments, theone or more electrodes 17, 19 are ring electrodes or tip electrodes. Insome embodiments, each of the electrodes 17, 19 are electricallyconnected to at least one of the one or more electrical contacts 16 onthe proximal connector body 13, as further discussed below.

In some embodiments, the fixation helix 9 is rotatably fixed withrespect to the lead body 3. In some such embodiments, the lead body 3 istorquable, allowing the fixation helix 9 to be implanted in body tissueby bringing the fixation helix 9 into contact with body tissue andtorquing the lead body 3 to provide torque to the fixation helix 9. Asthe fixation helix 9 is turned, the fixation helix 9 essentially screwsinto body tissue at the target location.

In other embodiments, and as best shown in FIG. 2 (described below), thefixation helix 9 is rotatable with respect to the lead body 3. Further,as best shown in FIG. 5 (also described below), in some embodiments theterminal pin 14 is rotatable with respect to the proximal connector body13 and the lead body 3. As described in detail below, in someembodiments the terminal pin 14 is connected to the fixation helix 9such that providing torque to the rotatable portion of the terminal pin14 imparts a torque on the fixation helix 9, facilitating theimplantation of the fixation helix 9 at a desired location. Further, insome embodiments the fixation helix 9 is also provided with a mechanismthat facilitates the extension and retraction of the fixation helix 9from the lead body distal portion 5.

In some embodiments, the lead 1 is adapted to supply an electrical shockto a patient's heart via one or both of the electrodes 17, 19. In somesuch embodiments, the electrodes 17, 19 include a coil. In addition, insome embodiments the lead 1 is also adapted to provide a cardiac pacingsignal and/or sense the electrical signals of a heart. For example, oneor more of the fixation helix 9, a portion of the electrodes 17, 19, oroptional additional electrodes such as ring electrodes (not shown) areconfigured to act as the poles of a pacing or sensing circuit. In someunipolar embodiments, one or more of the fixation helix 9, a portion ofthe electrodes 17, 19, and/or optional additional electrodes are adaptedto act as one pole of the pace/sense circuit and the other pole of thepace/sense circuit is provided at a remote location within the patient'sbody or on the surface of the patient's body. In some bipolarembodiments, one or more of the fixation helix 9, a portion of theelectrodes 17, 19, and/or optional additional electrodes are adapted toact as one pole of the pace/sense circuit and another of the fixationhelix 9, a portion of the electrodes 17, 19 and/or optional additionalelectrodes are adapted to act as the other pole of the pace/sensecircuit. For example, in some embodiments the fixation helix 9 isadapted to act as one pole of a bipolar pace/sense circuit and a portionof one or both of the electrodes 17, 19 and/or one or more optionaladditional ring electrodes are adapted to act as the other pole of thebipolar pace/sense circuit.

FIG. 2 shows a longitudinal cross-section of a distal portion of thelead 1 according to some embodiments of the present invention. FIGS. 3and 4A-4C show cross-sections of the lead body 3 at certain longitudinalpositions along the lead 1. As mentioned above, the lead 1 has afixation helix 9 disposed on a lead body distal portion 5. The lead body3 includes an elongate tubular member 21 that defines multiple lumens(as best shown in FIG. 3). In some embodiments, the multilumen tube 21forms a central or inner portion of the lead body 3 and extends from aproximal portion to a distal portion of the lead body 3.

As shown in FIG. 2, the multilumen tube 21 has a tubular wall whichdefines a first lumen 22. The multilumen tube 21 has a first portion inwhich a first number of lumens are defined (shown best in FIG. 3) and asecond, reduced dimension portion 23 in which a second number of lumensis defined (shown best in FIGS. 4A-4C). As shown in FIGS. 3 and 4A-4C,the first number of lumens is greater than the second number of lumens.In some embodiments, the multilumen tube 21 forms a continuous (i.e.,monolithic) wall that extends along both the first portion and thesecond, reduce dimension portion 23. For example, the reduced dimensionportion 23 is formed starting with a continuous (i.e., monolithic)multilumen tube and cutting away a portion of the multilumen tube 21, asfurther discussed below. As shown in FIGS. 3 and 4A-4C, in someembodiments the number of lumens in the first portion of the multilumentube 21 is three lumens and the number of lumens in the reduceddimension portion 23 is one. However, the number of lumens in these twoportions can vary depending on the application.

In some embodiments, the first lumen 22 extends through the multilumentube 21 from a proximal end to a distal end of the multilumen tube 21.As shown in FIG. 2, in some embodiments the first lumen 22 extendsthrough both the first portion of the multilumen tube 21 and the reduceddimension portion 23 of the multilumen tube 21. In some embodiments, thereduced portion 23 has a reduced outer dimension relative to the portionof the multilumen tube 21 immediately proximal to the reduced portion23. As shown in FIG. 2, in some embodiments the reduction in outerdiameter that forms the reduced portion 23 is an abrupt change in outerdimension of the multilumen tube 21. In other embodiments, this changein outer dimension is gradual or it is reduced in a stepped manner.

In addition, in some embodiments the multilumen tube 21 comprises aflexible and/or stretchable material, for example silicone orpolyurethane or any other suitable material. As further discussed below,in some embodiments stretchable material allows the reduced dimensionportion 23 to be stretched in order to place the reduced dimensionportion 23 over another portion of the lead 1.

The lead body distal portion 5 also includes a distal tip portion 26that includes a distal outer member 27 and an insert 28. In someembodiments, the distal outer member 27 is attached to the multilumentube 21. As shown in FIG. 2, the distal outer member 27 attaches to aconnector member 29. The connector member 29 is in turn connected to themultilumen tube 21, and in some embodiments also connects to a distalend of the electrode 17. For example, the connector member 29 has aproximal flange portion 31 and a distal flange portion 33. The electrodedistal end extends over and is attached to the proximal flange portion31. A proximal portion of the distal outer member 27 extends over and isattached to the distal flange portion 33. In other embodiments, thedistal outer member 27 and/or the electrode 17 attaches directly to themultilumen tube 21, or it attaches to another portion of the lead body3.

Further, the insert 28 is sized and configured to fit within, and isaffixed to, the distal outer member 27. In some embodiments, a distalend 37 of the insert 28 is shaped and configured to fit around thedistal end of the distal outer member 27, forming a distal leading edgeof the lead body 3. As shown in FIG. 2, the distal end 37 has roundededges, providing for a generally atraumatic shape on the distal end ofthe lead body 3.

In addition, in some embodiments a distal portion of the distal outermember 27 has a reduced inner diameter relative to a proximal portion ofthe distal outer member 27. As shown in FIG. 2, a proximal portion 39 ofthe insert 28 extends proximal of this reduced inner diameter portion,forming a space between the inner surface of the distal outer member 27and the outer surface of the insert proximal portion 39. In someembodiments, the space is an annular space, and the reduced portion 23is radially expanded or stretched and disposed around the insertproximal portion 39. In some embodiments, as shown in FIG. 2, thereduced portion 23 forms a lap joint with the insert proximal portion39. For example, a friction fit is formed therebetween and/or anadhesive is placed between the reduced dimension portion 23 and theinsert 28.

In some embodiments, a fixation member 42 includes both the fixationhelix 9 and a fixation helix base 43. The fixation helix base 43 isdisposed within the insert 28, and the fixation helix base 43 has afixation helix seating portion 45. In some embodiments, the seatingportion 45 is a reduced dimension portion of the fixation helix base 43,facilitating the attachment of the fixation helix 9 to the fixationhelix base 43 while still allowing the fixation member 42 as a whole totranslate in and out of the insert 28.

As shown in FIG. 2, the fixation helix base 43 also has first threads 47formed on an outer surface of the fixation helix base 43. In addition,second threads 48 are formed on an inner surface of the insert 28. Thefirst and second threads 47, 48 are shaped and configured tomechanically engage one another such that rotating the fixation helixbase 43 with respect to the lead body 3 (e.g., with respect to theinsert 28), causes the fixation member 42 to move longitudinally withrespect to the lead body 3 (e.g., with respect to the insert 28).

As shown in FIG. 2, the fixation helix base 43 defines a proximalopening 49. Further, extending through the first lumen 22 of themultilumen tube 21 is a conductor member 51. The conductor member 51extends into, and is electrically coupled to, the fixation member 42(e.g., electrically coupled within the opening 49 of the fixation memberbase 43, as shown).

In addition to electrically coupling to the fixation member, in someembodiments the conductor member 51 is also a torque transmissionmember, and the distal portion of the conductor member 51 ismechanically coupled to the fixation helix base 43. As discussed in moredetail below, in some embodiments the conductor member 51 extendsproximally to, and is mechanically coupled to, a rotatable portion ofthe terminal pin 14. The conductor member 51 transmits torque from arotatable portion of the terminal pin 14 to the fixation member 42. Asmentioned above, turning the fixation helix base 43 within the insert 28causes the fixation member 42 as a whole to simultaneously rotate andmove longitudinally, facilitating the implantation of the fixation helix9. In some embodiments, the conductor member 51 is a coil member and thecoil member is elongateable in order to accommodate the longitudinalmovement of the fixation member 42.

As mentioned above, in some embodiments the fixation member 42 iselectrically coupled to the conductor member 51. In some suchembodiments, the fixation helix 9 is an active fixation helix. Forexample electric signals are transmitted between the fixation helix 9and a portion of the terminal pin 14 via the conductor member 51. Assuch, the contact 15 on the terminal pin 14, the conductor member 51,the fixation helix base 43 and the fixation helix 9 are all electricallyconductive such that a first electric pathway is formed between thecontact 15 and the fixation helix 9.

In addition, as shown in FIGS. 2-4C, the conductor member 51 defines alumen 55. In some such embodiments, a stylet (not shown) is provided,and the stylet is sized and configured to be disposed within the lumen55. Further, in some embodiments the stylet is torqueable andfacilitates the transfer of torque and/or axial force from the terminalpin to the fixation helix 9. In other embodiments, the stylet may imparta shape to the lead 1 and/or the stylet may impart increased stiffnessto certain portions of the lead 1.

FIGS. 3 and 4A-4C show cross-sections of the multilumen tube 21according to various embodiments of the present invention. It is notedthat, although FIG. 2 indicates that FIGS. 3 and 4A-4C showcross-sections of the entire lead 1, for clarity FIGS. 3 and 4A-4C showonly the multilumen tube 21 and the conductor member 51.

FIG. 3 shows a cross section of the multilumen tube 21 that has not beencut down or reduced in outer dimension. As shown, in some embodimentsthe multilumen tube 21 has three lumens 22, 61, 63. In otherembodiments, the multilumen tube 21 has a single lumen, two or morelumens (e.g., lumen 22 with one lumen generally vertically aligned withlumen 22), three or more lumens, four or more lumens, or any othersuitable number of lumens. Further, in some embodiments one or more ofthe lumens are offset from the longitudinal axis of the multilumen tube21. For example, the first lumen 22 has a longitudinal axis that isnon-coaxial with respect to the longitudinal axis of the multilumen tube21. As further discussed below, in some embodiments the lumens 61, 63provide a passageway through which conductors can pass and theconductors electrically connect one or more of electrodes 17, 19 to theone or more electrical contacts 16.

FIGS. 4A-4C show cross-sections of the reduced dimension portion 23 ofthe multilumen tube 21. The portions of the multilumen tube 21 thatremain after portions of the tube have been cut away are shown using across-hatched pattern. FIG. 4A shows one embodiment of a reduceddimension portion that results from removing material from themultilumen tube 21 generally along three planes. The cuts are made inorder to both reduce the outer dimension of the multilumen tube 21 andreduce the number of lumens along a reduced dimension portion 23 of themultilumen tube 21. FIG. 4B shows another embodiment of a reduceddimension portion that results from removing material from themultilumen tube 21 generally along two planes. The two flat portions ofthe reduced dimension portion 23 indicate where the two portions ofmaterial are removed, forming a reduced dimension portion of themultilumen tube 21 that has a reduced number of lumens. FIG. 4C showsyet another embodiment of a reduced dimension portion 23 that resultsfrom removing material from the multilumen tube 21 in order to form around cross-sectional shape in the reduced dimension portion 23.

In addition, other cross-sectional shapes are possible for the reduceddimension portion 23 and for the other reduced dimension portionsdescribed herein. For example, in some embodiments, material is removedfrom the multilumen tube along a single plane. In some embodiments thereduced dimension portion 23 and the other reduced dimension portionsdescribed herein define more than one lumen. In other embodiments, thereduced dimension portion 23 has no lumen extending therethrough (e.g.,the lumens terminate at the reduced dimension portion). In addition,although embodiments described above generally refer to a multilumentube, other embodiments in which the tube has a single lumen are alsocontemplated. In some such embodiments, the single lumen continuesthrough the reduced dimension portion (the single lumen has a reducedthickness wall), while in other embodiments the reduced dimensionportion does not contain the lumen (e.g., the lumen terminates at thereduced dimension portion and the reduced dimension portion has a solidcross-section).

As shown in FIG. 2, the reduced dimension portion 23 is stretched orexpanded in order to be disposed around a portion of the distal tipportion 26 (e.g., the insert 28). As such, the lumen 22 formed by themultilumen tube 21 is continuous, and extends from a proximal portion ofthe multilumen tube 21, through the reduced dimension portion 23 of themultilumen tube 21 and connects to the insert 28. In addition, in someembodiments the joint between the reduced dimension portion 23 and thedistal tip portion 26 forms a fluid tight seal in order to preventfluids from entering the lumen 22. In some embodiments, this fluid tightlumen 22 prevents interference with the electrical signals that arebeing passed along the conductor member 51. As such, a fluid-tightpathway extends through the lumen 22 from the proximal portion of themultilumen tube 21, through the reduced dimension portion 23 and furtherthrough the distal tip portion 26 to the fixation member 42. An O-ringor some other type of seal (not shown) may also be placed between thefixation member 42 (e.g., the fixation helix base 43) and the insert 28in order to prevent fluids from entering the fluid-tight pathway throughthe distal end of the lead 1.

In addition, as shown in FIG. 2, a space 57 is formed within the lead 1around the reduced dimension portion 23. In some embodiments, this space57 is kept open, while in other embodiments the space 57 is partially orentirely filled, for example with a medical adhesive or other suitablefiller material. In addition, in some embodiments a space 58 is formedwithin the reduced dimension portion 23. In some embodiments, this space58 is kept open in order to allow for the rotation of the conductormember 51. In other embodiments, the space 58 is partially or entirelyfilled, for example with a medical adhesive or other suitable filler.

In the embodiment shown in FIG. 2, the reduced dimension portion 23 isstretched or expanded in order to be disposed around a portion of thedistal tip portion 26 (e.g., the proximal end 39 of the insert 28). Asshown, a space is formed between the insert proximal end 48 and theinner surface of the distal outer member 27. In other embodiments, theinsert proximal end 39 has a portion with a reduced outer dimension inorder to facilitate the placement of the reduced dimension portion 23 ofthe multilumen tube 21 over the insert 28. For example, the insertproximal end 39 may have a portion that is tapered or stepped down to asmaller outer dimension so that the reduced dimension portion 23 isrequired to be stretched or expanded a lesser amount relative to theembodiment shown in FIG. 2. As another example, a separate extensionmember (not shown) may extend proximally from the distal tip portion 26(e.g., from the insert proximal portion 39) and the separate extensionmay be tapered or stepped down to a smaller outer dimension.

FIG. 5 shows a longitudinal cross-section of the proximal connector 11of the lead 1 according to some embodiments of the present invention. Asmentioned above, the proximal connector 11 has a connector body 13 and aterminal pin 14 extending proximally from the connector body 13. Aportion of the outer surface of the terminal pin 14 defines a firstelectrical contact 15.

As shown in FIG. 5, the terminal pin 14 has an outer body portion 65surrounding an inner body portion 67. A portion of the inner bodyportion 67 extends proximally from the outer body portion 65, formingthe first electrical contact 15. In addition, in some embodiments theinner body portion 67 has an outer shape that mechanically interactswith an inner shape of the outer body portion 65, maintaining the innerbody portion 67 in a longitudinally fixed position while allowingrotation of the inner body portion 67 with respect to the outer bodyportion 65. For example, the inner body portion 67 has one or more, ortwo or more annular shaped protrusions 69 formed thereon. Further, theouter body portion 65 has annular grooves that correspond to the one ormore annular protrusions 69. The grooves and protrusions mechanicallyinteract to allow the inner body portion 67 to rotate within the outerbody portion 65.

The connector body 13 has a proximal portion 71. In some embodiments,the connector body proximal portion 71 surrounds, and is affixed to, theouter body member 65 of the terminal pin 14. In addition, one or moreelectrical contacts 16 are disposed on the connector body 13, forexample embedded in the connector body 13. As shown in FIG. 5, theconnector body 13 also has an insulative portion 73 that is disposedbetween the electrical contacts 16 in order to electrically isolate theelectrical contacts 16 from one another.

In addition, as shown in FIG. 5, in some embodiments a distal portion ofthe connector body 13 surrounds, and is affixed to, other portions ofthe lead body proximal portion 7, for example the multilumen tube 21and/or a lead outer layer 76. The multilumen tube 21 has a reduceddimension portion 79, which in some embodiments is similar to any of thereduced dimension portions 23 described above. Similar to the reduceddimension portion 23, the reduced dimension portion 79 is formed by acontinuous (i.e., monolithic) portion of the wall of the multilumen tube21. The wall is continuous (i.e., monolithic) from adjacent to thereduced dimension portion 79 and through the reduced dimension portion79 and in some embodiments the continuous wall extends the entire, orsubstantially the entire length of the multilumen tube 21.

Similar to the reduced dimension portion 23, the reduced dimensionportion 79 can also be stretched in order to be placed over a portion ofthe proximal connector 11. For example, as shown in FIG. 5, a proximalend of the reduced dimension portion 79 is stretched to create a largerinner opening. The larger inner opening is sufficiently large to fitover a distal portion of the outer body portion 65 of the terminal pin14, for example forming a lap joint between the outer body portion 65and the reduced dimension portion 79. The joint between the outer bodyportion 65 and the reduced dimension portion 79 can be formed byfriction fit or with the use of adhesive, or with any other suitabletechnique. In some embodiments, the joint between the outer body portion65 and the reduced dimension portion 79 facilitates the formation of afluid tight lumen from the outer body portion 65, through the firstlumen 22 of the multilumen tube 21, to the tip of the lead, as describedabove with respect to FIG. 2. Also, as mentioned above with respect tospaces 57, 58, the space 81 and/or the space 83 may be left open oreither or both of the spaces 81, 83 may be filled with a medicaladhesive or another suitable material.

Further, as discussed above, the multilumen tube 21 defines a firstlumen 22 through which the conductor member 51 extends and in someembodiments the conductor member 51 is rotatable with respect to themultilumen tube 21. The conductor member 51 extends proximally to theinner body portion 67 and is affixed to the inner body portion 67,which, as mentioned above, is rotatable with respect to the outer bodyportion 65 (and, as such, is rotatable with respect to the proximalconnector 11 and the lead body proximal portion 7). As such, torque canbe transmitted from the inner body portion 67 of the terminal pin 15 tothe fixation helix 9 via the conductor member 51.

FIG. 6 shows a longitudinal cross-section of the lead body near aproximal end of an electrode 17 according to some embodiments of thepresent invention. The electrode 17 includes a coil 90 and a fitting 91.The fitting 91 is disposed along the lead 1, and the fitting 91 has adistal flange portion 93 and a proximal flange portion 95. The proximalend of the coil 90 extends over the distal flange portion 93 and isaffixed to the distal flange portion 93 by any of a variety of methodsknown in the art, including by mechanical fit, by adhesive, by welding,brazing, soldering, crimping, or staking, or by any other suitablemethod. In some embodiments, affixing the coil electrode 17 to thefitting 91 forms an electrical connection therebetween. In someembodiments, a portion of lead 1 (e.g., the outer layer 76) extends overthe proximal flange portion 95. The portion of the lead 1 extending overthe proximal flange portion 95 is affixed to the proximal flange portion95, for example by shrink fitting, by extrusion, by dip coating, byadhesive, or by any other suitable method.

The fitting 91 also has an eyelet 97, which provides a point ofconnection for a conductor member, as best shown in FIG. 7A and asfurther discussed below. The multilumen tube 21 extends through thefitting 91. For example, the multilumen tube 21 has a reduced dimensionportion 99, which can be similar in cross-sectional shape to any of thereduced dimension portions described above. Further, as mentioned abovewith respect to reduced dimension portions 23 and 79, reduced dimensionportion 99 is defined by a wall of the multilumen tube 21, the wallbeing a continuous (i.e., monolithic) wall from adjacent the reduceddimension portion 99 and through the reduced dimension portion 99. Insome embodiments, the multilumen tube 21 is reduced in dimension onlythrough the fitting 91 (as shown in FIG. 6), and in other embodimentsthe multilumen tube 21 is reduced in dimension through the fitting 91and distal of the fitting 91. The reduced dimension portion 99 is sizedto fit through the open area 100 of the fitting 91, as shown best inFIGS. 7A and 7B. In some embodiments the open area 100 within thefitting 91 that is not occupied by the reduced dimension portion 99remains open, while in other embodiments the open area 100 is entirelyor partially filled with a medical adhesive or with another suitablefiller material.

As described above, the multilumen tube 21 defines the first lumen 22along with the second lumen 63. Extending through the first lumen 22 isthe conductor member 51, while a second conductor member 101 extendsthrough the second lumen 63.

Shown in FIGS. 7A and 7B are cross-sections of FIG. 6. FIG. 7A shows theeyelet 97 defining an opening 102. The eyelet 97 is slightly offset fromthe longitudinal axis of the fitting 91, which in some embodimentsensures that the eyelet 97 is aligned with the second lumen 63. As such,the second conductor member 101 can extend into the opening 102. In someembodiments, the second conductor 101 is affixed to the eyelet 97, forexample by welding, soldering, crimping or staking, or by any othersuitable method. In some embodiments, affixing the second conductormember 101 to the eyelet 97 forms an electrical connection. As such, anelectrical pathway is formed from the second conductor 101, to thefitting 91, and to the electrode 17. In addition to the fittingsdescribed herein, a variety of other types of fittings may be used tofacilitate the connection of a conductor member to a ring electrode orcoil electrode. For example, U.S. Patent Application No. 61/074,304,titled “Methods and Devices for Joining Cables,” filed Jun. 20, 2008describes some such fittings, and is incorporated by reference herein inits entirety.

As shown in FIG. 7B, the reduced dimension portion 99 extends throughthe fitting 91, and is surrounded by the space 100, which, as mentionedabove, in some embodiments is partially or entirely filled by a fillingmaterial. In addition, the reduced dimension portion 99 can be circularin cross-section (as shown in FIGS. 6-7B), or it can be one of theshapes shown in FIGS. 4A and 4B, or any other suitable shape.

Further, in embodiments where more than one electrode is disposed alongthe lead 1, more than one lumen is maintained through the fitting inorder to provide a passageway for a conductor member to reach the distalelectrode(s). As such, the reduced dimension portion 99 has any desiredcross-sectional shape, and may define zero, one or more, two or more, orthree or more, lumens.

Further, in some embodiments the conductors that extend from theelectrodes 17, 19 to the contacts 16 (e.g., the second conductor 101)are attached to the contacts 16 in a manner similar to that describedwith respect to FIGS. 6-7B. For example, in some embodiments, thecontacts 16 are formed from an outer surface of a ring-like structuresuch as the fitting 91 described above. In this manner, an electricalpathway is formed between one or more of the contacts 16 and one of theelectrodes 17, 19.

The embodiments above have been described with respect to leads thatcomprise shocking electrodes. In some embodiments, in addition to, or inplace of, the shocking electrodes, the lead 1 has ring electrodes, andthe ring electrodes are disposed along the lead body similar to thefitting 91 shown in FIG. 6. The ring electrodes may be adapted forpacing and/or sensing electrical signals of the heart, for example foruse as a pacing lead. In some such embodiments, electrical conductorsare attached to the ring electrodes in a manner similar to that shown inFIGS. 6-7A. Further, although the fixation helixes discussed above aredescribed as active helixes, they may also be passive (i.e.,non-electrically active). Other fixation mechanisms known in the art mayalso be used in place of the fixation helix.

In another embodiment of the present invention, a method ofmanufacturing a lead includes providing a multilumen tube (e.g., any ofthe multilumen tubes described above) and removing a portion of amultilumen tube to form a reduced dimension portion, for example any ofthe reduced dimension portions mentioned above.

In a method of the present invention, a multilumen tube is provided, forexample any of the multilumen tubes described above in which the one ormore of the lumens is eccentrically disposed in the multilumen tube. Forexample, the first lumen 22, as shown best in FIGS. 2 and 3, has alongitudinal axis that is offset from the longitudinal axis of themultilumen tube 21. As such, in order to remove material from themultilumen tube 21 and create a reduced dimension portion that maintainslumen 22 and is substantially aligned with the longitudinal axis of thelumen 22, the multilumen tube 21 is rotated about the longitudinal axisof the lumen 22 when removing material from the multilumen tube 21. Forexample, a portion of the cross-section of the multilumen tube 21 isremoved along a desired length of the multilumen tube 21, the multilumentube 21 is rotated about the longitudinal axis of the lumen 22, andanother portion of the cross-section of the multilumen tube 21 isremoved. This process can be repeated any number of times, for examplemaking two or more, three or more, or four or more cuts or ablations. Ifa large number of cuts or ablations are made and the multilumen tube 21is rotated a relatively small amount between cuts or ablations, across-section of the reduced dimension portion may have a substantiallyround outer shape, as shown in FIG. 4C.

FIG. 8 shows a fixture 111 for removing a portion of a multilumen tube.The fixture 111 has a support with a first side 113 and a second side115. The first side 113 has a first head 117 and the second side 115 hasa second head 125. The first head 117 has jig 119 affixed thereto, andthe jig 119 has one or more, two or more, three or more, or four or morelongitudinal jig members. For example, as shown in FIG. 8, the jig 119has a first longitudinal jig member 121, a second longitudinal jigmember 123 and a third longitudinal jig member 124. In some embodiments,the longitudinal jig members 121, 123, 124 are rods, while in otherembodiments the longitudinal jig members 121, 123, 124 are tubularmembers, or they are any other suitable longitudinal member. In someembodiments, each of the longitudinal jig members 121, 123, 124 areaffixed to the first head 117 and extend across toward the second head125. As shown in FIG. 8, the first longitudinal jig member 121 is longerthan the other longitudinal jig members 123, 124, and in some suchembodiments the second and third longitudinal jig members 123, 124 arethe same length. Further, in some embodiments, the first longitudinaljig member 121 has a greater outer dimension than the second and thirdlongitudinal jig members 123, 124.

In some embodiments, the number, size and configuration of thelongitudinal jig members are adapted to match with the number, size andconfiguration of the lumens of the multilumen tube. For example, thefirst longitudinal jig member 121 is sized and configured to fit withinthe first lumen 22 of the multilumen tube 21, the second longitudinaljig member 123 is sized and configured to fit within the second lumen63, and the third longitudinal jig member 124 is sized and configured tofit within the third lumen 61.

The second head 125 has a bottom portion 127 and a top portion 129. Insome embodiments, the top and bottom portions are openable with respectto one another, for example as disclosed in U.S. Pat. No. 7,271,364,filed Sep. 18, 2007, entitled “Laser Welding Fixture and Method,” whichis herein incorporated by reference in its entirety. In someembodiments, one or more of the longitudinal jig members 121, 123, 124extend to, or extend close to, the second head 125. In some otherembodiments, the longitudinal jig members 121, 123, 124 extend to, andinto, the second head 125. In some embodiments, the first and secondheads 117, 125 are driven (e.g., by a motor) and they are coordinatedsuch that they are rotated simultaneously at the same rate within thefixture 111.

A multilumen tube is fed over the jig 119 so that the longitudinal jigmembers 121, 123, 124 extend into the lumens of the multilumen tube. Forexample, the multilumen tube 21 is disposed over the jog 119 so that thefirst lumen 22 is disposed on jig member 121, the second lumen 63 isdisposed on jig member 123 and the third lumen 61 is disposed on jigmember 124. The jig member 121 is centered on the heads 117, 125. Themultilumen tube extends through a channel (not show) in the second head125 and, in some embodiments, through all or a portion of the side 115.

In order to remove material from the multilumen tube, any suitablecutting or ablating apparatus may be used. For example, in someembodiments the cutting or ablation apparatus (not shown) is a physicalablation tool (e.g., a grinder) or a laser. In some embodiments, thecutting or ablation apparatus is positioned in order to ablate or cutmaterial away from the multilumen tube along the longitudinal jig member121 that is centered on the heads 117, 125. In some embodiments, thecutting or ablation apparatus moves within the fixture 111 in order tofacilitate cutting or ablating along a desired length of the multilumentube. In some embodiments, the cutting or ablating apparatus cuts orablates along the multilumen tube, forming a generally flat surfacealong the multilumen tube (as shown in FIGS. 4A and 4B). The fixture 111can be used to rotate the multilumen tube about the longitudinal axis ofthe lumen in which the first jig 121 is disposed, and a second cut orablation is performed. This can be repeated a number of times and at thenecessary angles to form the desired shape. In some embodiments, themultilumen tube is cut or ablated numerous times and the multilumen tubeis rotated a small amount between cuts or ablations in order to form areduced dimension portion with an outer surface that defines asubstantially round cross-section (see, for example, FIG. 4C). Further,in some embodiments the multilumen tube with one or more reduceddimension portions is then incorporated into a lead as shown in FIGS.1-7B and as described above.

In some embodiments in which the reduced dimension portion is formedalong an intermediate portion of the multilumen tube (e.g., as shown inFIG. 6), the multilumen tube (including the reduced dimension portion)is stretched in order to neck down the entire multilumen tube. Thereduced dimension of the entire multilumen tube allows a fitting or aring electrode to be passed over the multilumen tube and disposed in thereduced dimension portion, as shown in FIG. 6. In some embodiments, aring electrode or a fitting is a continuous, unbroken ring of materialthat is placed in the reduced dimension portion in this manner.

In some embodiments, some of the leads described above can have thecapability both to shock the heart and pace and/or sense the rhythm ofthe heart. For example, in some embodiments the lead 1 shown in FIG. 1has multiple shock coils 17, 19 disposed thereon along with a fixationhelix 9. The fixation helix 9 is electrically coupled to the terminalpin contact 15, whereas the shock coils 17, 19 are each electricallycoupled to one of the connector body contacts 16. In some suchembodiments, the lead 1 is adapted to shock a heart using one or both ofthe shock coils 17, 19. In addition, a portion of one or both of theshock coils 17, 19 (e.g., a fitting at one end or both ends of one orboth of the shock coils 17, 19) is adapted to be one pole of apace/sense circuit. In some embodiments, the other pole of thepace/sense circuit is the fixation helix 9. In other embodiments, aportion of one or both of the shock coils 17, 19 and/or the fixationhelix 9 are configured to operate as one pole of the pace/sense circuitand the other pole of the pace/sense circuit is disposed at anotherlocation within the patient's body or on an outer surface of thepatient's body.

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer toparticular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present invention is intended to embrace all suchalternatives, modifications, and variations as fall within the scope ofthe claims, together with all equivalents thereof.

1. A medical lead comprising: a multilumen tube having a distal end and a proximal end and a wall, the wall defining at least three lumens along a first longitudinal portion of the tube and less than three lumens along a second longitudinal portion of the tube, wherein a first, continuous lumen extends through both the first and second portions, wherein the wall is substantially continuous through both the first and second longitudinal portions; a proximal connector disposed at the proximal end of the medical lead, the proximal connector adapted to connect the lead to an implantable medical device; a fixation member disposed on a distal end of the lead body, the fixation member having a fixation helix that is adapted to fix the lead at a site within a patient; a conductor member disposed in the continuous lumen and electrically coupling the proximal connector to the fixation member; and a distal tip portion, the fixation member at least partially disposed within the distal tip portion; wherein the second portion of the multilumen tube is connected with the distal tip portion, providing a fluid-tight passageway extending through the first and second portions of the multilumen tube and into the distal tip portion.
 2. The medical lead of claim 1, wherein the fixation member further has a fixation member base and the fixation helix is attached to a distal portion of the base and the conductor member is attached to a proximal portion of the base.
 3. The medical lead of claim 1, wherein the distal tip portion has a distal outer member and a distal inner member disposed within the distal outer member, wherein a space is formed between an outer surface of a proximal portion of the distal inner member and the inner surface of the distal outer member, and wherein the second portion of the multilumen tube is disposed within the space and forms a fluid tight seal with the distal inner member.
 4. The medical lead of claim 1, wherein the conductor member is a coiled torque transmission member and is affixed to the fixation member such that torque provided at a proximal portion of the conductor member is transmitted to the fixation member.
 5. The medical lead of claim 1, wherein the distal tip portion has an inner surface with first threads formed thereon and the fixation member has an outer surface with second threads formed thereon, the threads mechanically interacting such that turning the fixation member causes the fixation member to translate longitudinally with respect to the distal tip portion.
 6. The medical lead of claim 1, wherein the multilumen tube comprises a flexible material and wherein the second longitudinal portion of the multilumen tube is stretched to fit over a portion of the distal tip portion.
 7. The medical lead of claim 6, wherein the material is silicone.
 8. The medical lead of claim 1, wherein the proximal connector has a connector body and a terminal pin, wherein a portion of the terminal pin is rotatable with respect to the connector body and wherein a proximal end of the conductor member is coupled to the terminal pin such that torque imparted on the terminal pin is transmitted to through the conductor member to the fixation member.
 9. The medical lead of claim 1, wherein the second longitudinal portion of the multilumen tube defines a single lumen.
 10. The medical lead of claim 1, wherein the wall of the multilumen tube is continuous from the distal end to the proximal end of the multilumen tube.
 11. A medical lead comprising: a multilumen tube defining a first number of lumens along a first longitudinal portion of the tube and a second number of lumens along a second longitudinal portion of the tube, wherein the first number of lumens is larger than the second number of lumens, wherein a continuous lumen extends through both the first and second portions and wherein the wall is substantially continuous through both the first and second longitudinal portions; a fixation member disposed on a distal end of the lead body, the fixation member having a fixation helix that is adapted to fix the lead at a site within a patient; and a distal tip portion, the fixation member at least partially disposed within the distal tip portion; wherein a fluid tight seal is formed between the second portion of the multilumen tube and the distal tip portion, providing a fluid-tight passageway through the first and second portions of the multilumen tube, into the distal tip portion and to the fixation member.
 12. The medical lead of claim 11, wherein the fixation member has a fixation member base and the fixation helix is attached to, and extends distally from, the fixation member base.
 13. The medical lead of claim 11, further comprising a conductor member that is disposed in the continuous lumen, wherein a distal portion of the conductor member is electrically coupled to the fixation member.
 14. The medical lead of claim 11, further comprising a conductor member that is disposed in the continuous lumen, wherein a distal portion of the conductor member is electrically and mechanically coupled to the fixation member such that torque provided at a proximal portion of the conductor member is transmitted to the fixation member.
 15. The medical lead of claim 11, wherein the wall of the multilumen tube is continuous from the distal end to the proximal end of the multilumen tube.
 16. A method of manufacturing a medical lead comprising: providing a multilumen tube having a distal end and a proximal end and a first longitudinal axis, the tube defining a lumen that defines a second longitudinal axis that is non-coaxial with the first longitudinal axis; removing a first portion of a cross-section of the tube along a desired portion of the length of the tube while maintaining the lumen; rotating the multilumen tube about the second longitudinal axis and removing a second portion of a cross-section of the tube along the desired portion of the length of the tube; and incorporating the tube into a lead.
 17. The method of claim 16, wherein the multilumen tube defines more than one lumen and wherein removing the first and second portions of material reduces the number of lumens.
 18. The method of claim 16, wherein the removal is performed using a laser.
 19. The method of claim 16, wherein more than two portions of material are removed and the multilumen tube is rotated between the removing steps and wherein the cross-sectional shape of the finished reduced dimension portion is substantially round.
 20. The method of claim 16, further comprising: providing a fixture with a first fitting and a second fitting, the first fitting having a longitudinal jig that is shaped and sized to fit within the lumen, the second fitting having a channel through which the multilumen tube can extend, the first and second fitting configured to be simultaneously rotated about the longitudinal jig; placing the multilumen tube through the channel and on the longitudinal jig; removing the first portion of the cross-section of the tube along the desired portion of the length of the tube; rotating the multilumen tube about the longitudinal axis of the lumen by simultaneously rotating the first and second fittings; and after rotating the tube, removing the second portion of the cross-section of the tube along the desired portion of the length of the tube.
 21. The method of claim 16, further providing a distal tip portion of a lead and expanding the reduced dimension portion of the multilumen tube to fit around a portion of the distal tip portion, forming a fluid tight seal therebetween.
 22. The method of claim 21, wherein the reduced dimension portion forms a lap joint with the distal tip portion. 